That is the outlet heater hose. Replacement is not too difficult but you need to be careful with the heater joint as it can collapse easily. Use a plier to release the clamps and push them away from joint.
Use a sharp blade to slit the hose so that it can come off without damaging the heater joint which is very soft as it is made of copper. Twist the hose gently to unloosen first.
Before starting work, you need to drain the coolant first.
After replacement, remember to bleed the system by releasing the bleeder nut located at thermostat housing and topping up till coolant flows out. Retighten and do not close radiatior cap first.
Start engine and let it run for about 1 minute. Stop engine and top up coolant. Repeat process until when you stop the vehicle, the coolant remains full.
Friday, October 24th, 2008 AT 12:24 PM